The card catalog at the local public library was my first database. The catalog made it
possible to find books based on titles, authors, or subjects just like writing a SQL query.
Of course, I could walk around and locate books because they were arranged thanks to
the Dewey Decimal System, but having that old drawer-filled cabinet made it even easier.
Decades ago, most businesses did everything with paper stored in filing cabinets.
Computers and databases existed, but they were not commonly used in schools or many
businesses until the 1980s and 1990s. Now, it’s easy for almost anyone to keep track of
data in a local database or at least a spreadsheet.
The ability to query a database is vital for many professions. Of course, application
developers, database administrators, business intelligence developers, database
developers, and data scientists must be able to work with databases. What might be
surprising is that professionals working in human resources, insurance, health care,
government records, grant writing, publishing, real estate, and social work, to name a
few, now must query databases. I often run into these “nontech” professionals at SQL
Server events or the classes that I teach, so I know that SQL querying is an important
in- demand skill in many industries and positions.
There are several database vendors, and this book is meant to teach T-SQL, the
query language used for SQL Server and Azure SQL Database from Microsoft. Many
professionals will find that they end up working with other databases such as Oracle or
MySQL databases from time to time. The basics do carry from one system to another, but
each vendor supports its own extensions, or flavor, of the SQL language. For SQL Server,